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HealthScience

Resistant TB Strains Spreading in Europe, More Antibiotic Resistant Germs Emerging Worldwide

Mycobacterium tuberculosis
Scanning electron micrograph of Mycobacterium tuberculosis

New forms of Multi-drug Resistant Tuberculosis (MDR-TB) are spreading at “alarming rates” according to a new report issued by the World Health Organization (WHO). The return in force of this ancient disease could lead to a pandemic in Western Europe — killing thousands — if health authorities do not succeed in cutting off the bug’s spread in time.

The Report was presented at the 61st meeting of the WHO’s Regional Committee for Europe, in Azerbaijan. The committee is expected to introduce a comprehensive action plan to fight the new resistant forms of this old bacteria.

In a statement to the press, Zsuzsanna Jakab, the WHO’s Regional Director for Europe, said:

“TB is an old disease that never went away, and now it is evolving with a vengeance”.

The bacterium that causes tuberculosis (Mycobacterium tuberculosis) has both active and dormant forms. An estimated one in three people worldwide carries the dormant form. It it only when the germ becomes active that illness ensues. Generally, any condition that weakens the immune system (like HIV, old age) can trigger the active state which attacks the pulmonary system (lungs), primarily, but can also invade extra-pulmonary tissue in the body. TB is spread through “coughing sprays” consisting of tiny infected droplets that become airborne. But according to researchers, it usually takes multiple exposures to the germ before one contracts TB.

Unlike many other forms of bacteria that can divide every hour, the Mycobacterium has a very slow rate of of cell division — taking up to 20 hours in some cases for one cell to divide.

There are are 9 million new cases annually, with roughly 2 million of those dying.  This is largely due to a lack of the necessary standard drugs. The traditional form of disease is curable but requires a strict regimen of four,  “first line” drugs taken over a six month period, in quarantine. The new MDR-TB strains may take up to 2 years to treat, at a cost of 16, 000.00 USD per patient.

Tuberculosis symptoms, diagram
Main symptoms of variants and stages of tuberculosis,with many symptoms overlapping with other variants, while others are more (but not entirely) specific for certain variants. Multiple variants may be present simultaneously (chart by Mikael Häggström)

Warnings about the emergence of  “super bugs” go back more than ten years now, and the re-emergence of these new resistant strains of Mycobacteria in Eastern Europe and Russia have been reported as early as 2003. Currently, the heaviest burden of the disease, according to the report, will be born by Eastern European populations (including Russia and Ukraine), but rates of new cases of the MDR-TB strain are climbing fast in Western Europe.

According to a recent medicalnewstoday.com article * :

“…there are 3,500 cases of TB in London every year (2% of which are MDR-TB), the highest TB rate of any capital city in western Europe. The rate of MDR-TB in London doubled between 2005 and 2009.”

TB bacteria can survive extremely dessicated environs and flourish and evolve in certain others — such as unsanitary, poorly ventilated prisons — but the spread of super resistant germs, in general, is blamed on the over-use of antibiotics, whether in hospital settings (and through over-prescribing) or through the use of human antibiotics on livestock populations. The resistant stains usually develop in the animals and then jump to humans upon repeated contact.

In the case of TB, dormant forms of the bacteria can become activated through some other immune-weakening illness. The bacteria then come into contact with antibiotics being used to treat the original illness.

Many species of bacteria are capable of developing rapid resistance to drugs designed to kill them through genetic expression of key enzymes; others have a well-coordinated capacity for actually “pumping” the drugs out of the cell. Natural selection insures that any new resistant genotype (which controls the immune-evading behavior), will have a good probability of being passed on during cell division, or even “swapped” with nearby bacterial cells, through what’s known as horizontal gene transfer.

The ease of global travel — as depicted quite horrifically in the recent movie ‘Contagion’ — provides a perfect launch pad for the spread of new strains.

These new strains of Multi-drug Resistant Tuberculosis will make stopping the pandemic far more difficult,  as new drug “scaffolds” need to be engineered to build up new antibiotic compounds to combat the disease.

Jakab also stated that “complacency” had allowed the bug to become resistant and that the problem needed immediate action to prevent “huge human and economic costs.”

Authors of the WHO action plan believe that they will be able to save 120,000 lives and save billions of dollars (mostly in costs from treating and stopping early the MDR forms of the TB) by 2015. To achieve this, the plan will have to accomplish three goals:

  • Decrease by 20% the proportion of MDR-TB cases among previously treated patients,
  • Diagnose at least 85% of estimated MDR-TB cases, and
  • Successfully treat at least 75% of patients notified as having MDR-TB.

The report also  notes:

The Global Fund to Fight AIDS, Tuberculosis and Malaria has indicated that it strongly backs the action plan and is ready to provide financial support, where the affected countries step up their own financial commitment.”

Other Super  Germs Emerging:

And TB is not the only super-resistant bug on the rise. In early summer, the news of an antibiotic resistant gonorrhoea strain began making headlines. The new strain of this old, sexually transmitted disease (known as “the clap”) apparently first emerged in Japan, or possibly Korea.

Up until now, the disease was easily treatable with the CDC recommending a single dose of the antibiotic cefixime, or, a single dose of azithromycin (if allergic to penicillin, note:  is no longer considered an effective treatment) or ceftriaxone. The new strain, however, is resistant to every tested antibiotic, according to researchers presenting at the 19th conference of the International Society for Sexually Transmitted Disease Research,  in Quebec City, Canada, this past July.

comparison of Gram-positive and Gram-negative cell membrane composition
Comparison of Gram-positive and Gram-negative cell membrane composition (credit: Graevemoore at en.wikipedia)

Also, this past Spring, reports of a super-resistant strain of E. coli called NDM-1 began making medical science news. Harmless E coli bacteria, normally present in the human gut, had, according to one report, “swapped genes” with a more resistant form (discovered to be infecting nearly half of the rain water pools in one sampled location). The super E coli strain was first detected in India, but has now shown up  in the UK.

This super bug was similar, genetically, to the strain of E. coli that spread through central Europe this year that killed 51 people and sickened hundreds (traced to an organic sprouts farm in Lower Saxony, though the means of contamination has not been discovered). These two forms of the common gut bacteria possess a gene that produces an enzyme capable of breaking up antibiotics. It may be this gene — or a mutated form of it — which the ordinary E coli strain acquired at some point in its evolution, giving rise to the “superbug”, NDM-1.

These types of bacteria are known as Gram-negative bacteria which possess, in addition to a cell wall, an outer membrane layer composed of lipopolysaccharide (which Gram-positive bacteria do not possess) , making them more impervious to drugs. Other genera of Gram-negative bacteria include: Salmonella, Shigella, Pseudomonas, Moraxella, Helicobacter, Stenotrophomonas, Bdellovibrio, acetic acid bacteria, and Legionella .

Note that Mycobacteria tuberculosis is a Gram-positive bacteria, as it lacks an outer membrane, however, it is only weakly so, as its cell wall has a high lipid and mycolic acid content. This trait may be a contributor to its resistance capability.

*Resistant TB Spreading In Europe At Alarming Rate, WHO




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